1. Field of the Invention
The present invention relates generally to integrated-circuit memories.
2. Description of the Related Art
Access to static random access memories (SRAMs) and to read-only memories (ROMs) is required by various integrated circuits (e.g., digital signal processors, microcontrollers and field-programmable gate arrays). These memories are typically supplied as separate and distinct structures and fixed, pre-programmed data is generally stored in the read-only memory with variable data written into and read from the read/write memory.
In many applications, read-only memory is accessed infrequently yet it occupies significant integrated-circuit area. In addition, some applications of a specific integrated circuit require increased amounts of read-only memory while other applications require increased amounts of read/write memory and these conflicting needs are often unpredictable and unknown at time of integrated-circuit fabrication. Increasing both the read-only and the read/write memories has been a conventional response to these contrasting needs but this response is expensive and demands valuable integrated-circuit space.
The present invention is directed to read/write memory arrays that significantly enhance flexibility of memory allocation without increasing memory area nor significantly altering conventional read/write processes.
These goals are realized with a read/write memory that provides predetermined latent-state patterns which are retrieved with a latent-state retrieve process that differs somewhat from a conventional write process.